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          <th colspan="3" align="center">DbEnv::mutex_stat()</th>
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          <th width="60%" align="center">Chapter 10. 
                Mutex Methods 
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            <h2 class="title" style="clear: both"><a id="mutexstat"></a>DbEnv::mutex_stat()</h2>
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      <pre class="programlisting">#include &lt;db_cxx.h&gt;

int
DbEnv::mutex_stat(DB_MUTEX_STAT **statp, u_int32_t flags); </pre>
      <p>
         The <code class="methodname">DbEnv::mutex_stat()</code> method returns the mutex subsystem
         statistics.
    </p>
      <p>
         The <code class="methodname">DbEnv::mutex_stat()</code> method creates a statistical structure of
         type <code class="literal">DB_MUTEX_STAT</code> and copies a pointer to it into a user-specified
         memory location.
    </p>
      <p>
         Statistical structures are stored in allocated memory.  If
         application-specific allocation routines have been declared (see
         <a class="xref" href="envset_alloc.html" title="DbEnv::set_alloc()">DbEnv::set_alloc()</a> 
         for more information), they are used to allocate the memory;
         otherwise, the standard C library <span class="bold"><strong>malloc</strong></span>(3) is used.  The caller is responsible
         for deallocating the memory.  To deallocate the memory, free the
         memory reference; references inside the returned memory need not be
         individually freed.
    </p>
      <p>
         The following <code class="literal">DB_MUTEX_STAT</code> fields will be filled in:
    </p>
      <div class="itemizedlist">
        <ul type="disc">
          <li>
            <p>
                          <span class="bold"><strong>u_int32_t st_mutex_align;</strong></span>
                </p>
            <p>
                        The mutex alignment, in bytes.
                </p>
          </li>
          <li>
            <p>
                         <span class="bold"><strong>int st_mutex_cnt;</strong></span>
                </p>
            <p>
                        The total number of mutexes configured.
                </p>
          </li>
          <li>
            <p>
                         <span class="bold"><strong>u_int32_t st_mutex_free;</strong></span>
                </p>
            <p>
                        The number of mutexes currently available.
                </p>
          </li>
          <li>
            <p>
                         <span class="bold"><strong>u_int32_t st_mutex_init;</strong></span>
                </p>
            <p>
                    The initial number of mutexes configured.
                </p>
          </li>
          <li>
            <p>
                         <span class="bold"><strong>u_int32_t st_mutex_inuse;</strong></span>
                </p>
            <p>
                        The number of mutexes currently in use.
                </p>
          </li>
          <li>
            <p>
                         <span class="bold"><strong>u_int32_t st_mutex_inuse_max;</strong></span>
                </p>
            <p>
                        The maximum number of mutexes ever in use.
                </p>
          </li>
          <li>
            <p>
                         <span class="bold"><strong>u_int32_t st_mutex_max;</strong></span>
                </p>
            <p>
                        The maximum number of mutexes.
                </p>
          </li>
          <li>
            <p>
                        <span class="bold"><strong>u_int32_t st_mutex_tas_spins;</strong></span>
                </p>
            <p>
                         The number of times test-and-set mutexes will spin without blocking.
                </p>
          </li>
          <li>
            <p>
                         <span class="bold"><strong>uintmax_t st_region_wait;</strong></span>
                </p>
            <p>
                         The number of times that a thread of control was forced to wait before
                         obtaining the mutex region mutex.
                </p>
          </li>
          <li>
            <p>
                         <span class="bold"><strong>uintmax_t st_region_nowait;</strong></span>
                </p>
            <p>
                         The number of times that a thread of control was able to obtain the
                         mutex region mutex without waiting.
                </p>
          </li>
          <li>
            <p>
                         <span class="bold"><strong>roff_t st_regmax;</strong></span>
                </p>
            <p>
                    The max size of the mutex region size.
                </p>
          </li>
          <li>
            <p>
                         <span class="bold"><strong>roff_t st_regsize;</strong></span>
                </p>
            <p>
                        The size of the mutex region, in bytes.
                </p>
          </li>
        </ul>
      </div>
      <p>
              The <code class="methodname">DbEnv::mutex_stat()</code> method may not be called before the 
              <a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a>  method is called.
     </p>
      <p>
         The <code class="methodname">DbEnv::mutex_stat()</code> <span>
            
            <span>
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.
            </span>
        </span>
    </p>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp9279160"></a>Parameters</h3>
            </div>
          </div>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9269816"></a>statp</h4>
              </div>
            </div>
          </div>
          <p>
                  The <span class="bold"><strong>statp</strong></span> parameter references memory
                  into which a pointer to the allocated statistics structure is copied.
             </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9282728"></a>flags</h4>
              </div>
            </div>
          </div>
          <p>
                  The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
                  or the following value:
             </p>
          <div class="itemizedlist">
            <ul type="disc">
              <li>
                <p>
                          <code class="literal">DB_STAT_CLEAR</code>
                    </p>
                <p>
                        Reset statistics after returning their values.
                    </p>
              </li>
            </ul>
          </div>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp9287976"></a>Errors</h3>
            </div>
          </div>
        </div>
        <p>
             The <code class="methodname">DbEnv::mutex_stat()</code> <span>
            
            <span>
                method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> 
                exception, encapsulating one of the following non-zero errors, or return one
                of the following non-zero errors:
            </span>
        </span>
        </p>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp9281880"></a>EINVAL</h4>
              </div>
            </div>
          </div>
          <p>
                An invalid flag value or parameter was specified.
            </p>
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      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp9294720"></a>Class</h3>
            </div>
          </div>
        </div>
        <p>
            <a class="link" href="env.html" title="Chapter 5.  The DbEnv Handle">DbEnv</a>  
        </p>
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      <div class="sect2" lang="en" xml:lang="en">
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            <div>
              <h3 class="title"><a id="idp9291568"></a>See Also</h3>
            </div>
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        <p>
             <a class="xref" href="mutex.html#mutexlist" title="Mutex Methods">Mutex Methods</a> 
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